The present invention relates to a program linking system and, more particularly, to a system for partially linking a plurality of unit programs.
In a conventional computer system, in order to link a plurality of unit programs to form a single program having one execution format and to execute the single program, names of unit programs and names of means storing the unit programs are given to the computer system during linking. In conventional linking systems, if a unit program to be linked to a given unit program does not exist in the program storing means such as a program library, the program having an execution format is generated while the assigned program is not linked to the given program. During execution of the program, when control is shifted to the unit program assigned by control shift information such as a call instruction, an execution error occurs and the subsequent operation cannot be performed. When the execution error occurs, if the error is caused by nonlinkage of the assigned program or the error is caused by another cause cannot be determined.
The following schemes must be employed to execute only other linked unit programs without causing an execution error when the unit program assigned by the control shift information does not exist in the conventional program linking system.
(1) An original program is corrected so as not to call the unit program and then, linkage operation is performed again, and PA1 (2) A dummy program having a given name is generated for each nonexistent unit program and is stored in the program storing unit.
In a conventional scheme (1) described above, however, the original program must be corrected, and the operations are cumbersome. At the same time, errors may occur during correction.
In a conventional scheme (2) described above, the dummy program having a given name must be generated in units of nonexistent unit programs. When the number of nonexistent unit programs is increased, the number of dummy programs is increased, and preparation procedures are complicated. In addition, if the name is to be changed, the dummy program must be corrected.